I recently changed chainrings on my compact FSA SLK crankset. The Campy compact front derailleur (braze on) on this 2005 Giant TCR advanced frame has always been touchy for adjustment. It took a lot of work to get it adjusted to shift into the big ring smoothly and consistently without rubbing the crank but it has worked well for years and it seemed to be working fine after the chainring switch, on the work stand (no load), trainer (under load) and on the road (although I haven't ridden it much on the road since switching rings). But I was on the Kreitler rollers (with Headwind fan so also under load) while watching a world cup game and it would not shift into the big ring? I remounted the front der with a variety of subtle adjustments as much as I can do without rubbing the crank arm but no luck. The front cage is about as close as I can get to the teeth of the big ring. I have a another bike I ride more and could use on the rollers but this issue bugs the hell out of me. I've even played a bit with chain tension and the Campy A screw adjustment on the rear derailleur after revisiting Sheldon Brown's treatise on derailleur adjustment. I can adjust the front limit screw to go more outboard and get the crank rub and get it to shift and then trim it back but this isn't a very satisfactory solution. Any ideas?
I have to say I don't like the braze on mount on this bike. It seems a bit flexy even with the mount screws torqured properly from carbon flex in the seat tube. The new chain rings I put on do seem stiffer than the old ones.
FWIW. My verylimited experience with braze on front derailleur mounts (three Italian frames from two different marques) is they ALL needed to be tweaked to facilitate an easy-to-adjust front derailleur whereby the outer plate could be easily squared ...
That is, if one were to simply clamp the derailleur in place WITHOUT looking (in one of the three, fore mentioned frames AFTER I tweaked the braze on mount), the front derailleur's outer plate will be parallel to the frame's central plane (and, of course, the chainrings).
BTW. A Shimano 6500/6503 (or, equivalent 105 or Dura Ace 9-speed) front derailleur is a VERY GOOD substitute for a 10-speed Campagnolo front derailleur.
Thanks I'll double check that alignment. It's the difference between shifting on rollers that has be befuddled... The tolerance for this working or not without crank rub is so close that any subtle change in context seems to make a difference. But maybe the hanger alignment can widen the dynamic range....
